1. Field of the Invention
The present invention relates to a grinding method including a rough grinding process and a finish grinding process, and a grinding system and a multifunction grinding machine executed by the grinding method.
2. Description of the Related Art
It is disclosed in U.S. Pat. No. 5,392,566 that a multifunction grinding machine has a curved concave surface machined by a rough grinding wheel with a large diameter and a finish grinding wheel with a small diameter.
Since the U.S. Pat. No. 5,392,566 discloses that the rough grinding is executed by the large diameter of the rough grinding wheel and the finish grinding is executed by the small diameter of the finish grinding wheel, a removed amount for finish grinding in the curved concave surface of a workpiece is larger than that in remaining portion except for the curved concave surface after rough grinding by the rough grinding wheel. Therefore, it tends to make a variable grinding force by the finish grinding wheel in accordance with a rotational phase of the workpiece. Especially for a cam profile of a camshaft there is a larger removed amount for finish grinding in the curved concave surface than the removed amount for finish grinding in other portion from the curved concave surface, therefore it tends to make large grinding force in the curved concave surface of the cam profile. This causes a shorter life of the finish grinding wheel and a longer time in the finish machining process.
In general, a removed volume per time by the finish grinding is smaller than that by the rough grinding. Therefore, it is desirable that it executes the rough grinding by the rough grinding wheel more time as much as possible and the finish grinding by the finish grinding wheel less time as little as possible. However, there is some restriction by a machine construction or a cycle time of the machining line to decide the individual removed volume by the rough grinding wheel and the finish grinding wheel. Thereby it should increase the removed volume by the finish grinding wheel, so that the life of the finish grinding wheel is ceased faster than that of the rough grinding wheel. As a result, cost for the finish grinding wheel is increased.